The surface photometry of NGC 3379

Surface photometry is carried out for the photometric standard galaxy NGC 3379 on the basis of two plates in the blue band taken with the Bejing Schmidt telescope. The results, including luminosity profiles, photometric parameters, integrated luminosity distribution, ellipticity and position angle variation, are presented in various forms of figures and tables. Especially our geometric profiles, i.e., ellipticity and position angle variations reach up to 5, much fainter region than that any previous study did. The accuracy of the present data is checked by comparing them with the surface photometry in the literature. We find the zero-point 0.12 mag brighter than the calibration of de Vaucouleurs and Capaccioli (1979), which agrees with the values 0.10–0.15 mag difference claimed by recent observations. The systematic differences is found to be less than 0.1 mag.     

The distribution of interstellar matter in NGC 654

The young cluster NGC 654 is studied using UBV photographic photometry with a view to determining the distribution of interstellar matter in a region where star formation recently occurred.NGC 654 is found to be enclosed in a shell of interstellar matter of mass 1500M . The mass of all stars in the cluster is 4000M .     

B,V surface photometry of the UV continuum galaxy NGC 838

Surface photometry of the UV continuum galaxy NGC 838 has been carried out in theB, V system using photographic plates obtained with the 74 Kottamia telescope, Egypt. Isophotes, luminosity profiles, integrated photographic magnitudes, effective diameters and other photometric parameters are derived.The photoelectrically calibrated total apparent magnitudes areB _T =13.57 with maximum diameters 1.57×1.34 (at threshold _m =27.7 mag.//) andV _T =12.91 with maximum diameters 1.54×1.32 (at threshold _m =27.7 mag./). The integrated colour index(B–V) _T =0.66 and the effective surface brightness _e (B=19.0 mag./) and _e (V=19.7 mag./. The major axis is at position angle =85°±1°.The nucleus of NGC 838 is quite blue (integrated colour(B–V)=0.41 forr ^*<0.1) compared to normal galaxies while the colour becomes redder from the nucleus outwards. The UV excess, H emission and radio continuum emission previously observed from this galaxy by other investigators may be attributed to a recent burst of star formation in the nucleus of the galaxy of duration slightly greater than 2×10⁷ yr.     

The nitrogen abundance in NGC 55

The purpose of this paper is to propose an interpretation for the line spectrum of NGC 55, whose most remarkable feature is the absence of the generally noticeable 6584[Nii]. From the physical conditions of the ionized gas responsible of the observed emission, we infer that the N(N)/N(O) abundance ratio is significantly smaller than usual, probably reflecting a nitrogen underabundance in a medium of temperatures 9100 K and densities 500 cm^–3.     

Connection between X-ray and optical variability in NGC 4151

We have used long light curves in the X-ray (ARIEL V, EXOSAT, Ginga and others), UV (IUE), and optical (data of intensive ground-based monitoring) ranges of NGC 4151 to investigate connections between variations in these spectral fields. Applying Fourier (CLEAN algorithm) and modern cross-correlation analysis, we revealed the different character of the variability and the cross-correlation between high and low states of the nucleus. In contrast to earlier results, we found that X-ray and optical fluxes correlate in the active state without any apparent delay.In the power spectrum of the optical and X-ray light curves in the high state we found the existence of the same period of about 65 days, which disappeared in the low state.We confirmed previous data that X-ray variations correlate more strongly with UV and optical continuum variability during the low state, but it is possible that the optical variations appear to lag behind those involving X-rays by several tens of days.Strong variations in H line profile and [Fe X]6374 line intensity variations correlate with the observed X-ray covering dip in 1990 (Yaqoobet al., 1993).We discuss briefly the implications of these results.     

Continuum and reddening of the peculiar nucleus of NGC 5236

Photographic spectrophotometry andUBV multi-aperture photometry are used to analyze the stellar composition and gas content within a region of 12 arcsec in the nuclear bulk of the Sérsic-Pastoriza galaxy NGC 5236. An internal reddeningE(B–V)=0.2±0.1 mag. is derived for this region. A fail of the fit between the synthetic and the observed continuum for 5600Å6500 Å is discussed.     

Study ofUBV photometry of the Seyfert galaxy NGC 3227

Multi-apertureUBV photometry of NGC 3227 is presented. An interpolation formula based on the galaxy profile allows the reduction of all previous measurements to a standard aperture diaphragm.     

Der offene Sternhaufen NGC 5617

Zusammenfassung Der offene Sternhaufen NGC 5617 wurde nach dem Streifenverfahren auf Karten von photographischen Aufnahmen verschiedener Belichtungszeiten mit dem 1m-Schmidt-Teleskop des European Southern Observatory in Chile untersucht. Der Haufen enthält etwa 460 Sterne mit einer Gesamtmasse von 700 . Der Radius beträgt 3.7 pc, die Sterndichte im Zentrum 50 Sterne pc^–3, und die mittlere Sterngeschwindigkeit 0.89 km s^–1. Auf den länger belichteten Aufnahmen taucht im Abstand von 12.3 in Richtung SSE ein unbekannter offener Sternhaufen auf, der einen Radius von etwa 4.3 hat und etwa 150 Sterne bis zur GrenzgrößeV19^m enthält.

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The open cluster NGC 5617 was investigated by the strip method on charts of photographs with different exposure times taken with the 1-m Schmidt telescope of the European Southern Observatory. The cluster contains about 460 stars with a total mass of 700 . Its radius amounts to 3.7 pc; the star density in the center is 50 stars pc^–3; and the mean stellar velocity, 0.89 km s^–1. On longerexposed photographs at a distance of 12.3 in direction to SSE an unknown open star cluster becomes visible with a radius of 4.3, containing about 150 stars to the limiting magnitudeV19^m.

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Mitteilungen Serie A.     

Physical conditions in NGC 6164-5

From spectroscopic observations of the emission lines H, 4959 and 5007[Oiii], H, 6584[Nii], 6717 and 6731[Sii] and some interferometric data in H and [Nii] it was established that NGC 6164 and NGC 6165 have characteristics of normal Hii regions for Ne and Te. They are embedded in a very tenuous medium nearly coincident with the Strömgren sphere of the central star HD 148937, corresponding to the outer peripheral structure described by Westerlund. Variations of the relative abundances of N, O, and S are discussed.     

PhotoelectricUBV and DDO photometry of NGC 5138

Results ofUBV photoelectric photometry in NGC 5138 are presented for 50 stars brighter than 14.0 mag. In addition, four probable red giants were also observed in the DDO system. Sixteen stars previously considered members by Lindoff (1972), were found not to be physically connected with the cluster. NGC 5138 is located 1.80 kpc from the Sun and the visual interstellar absorption determined from the reddenedB stars amounts toA _v =0.75 mag. Three of the four red stars observed in the DDO system were found to be cluster members. The mean cyanogen anomaly is CN=0.043±0.018 (m.e.), which implies that NGC 5138 is richer in CN than the field K giants in the solar neighbourhood, but poorer than the Hyades giants. The cluster age is estimated to be 1.5×10⁸ yr.Member of the Carrera del Investigador Cientifico del Consejo Nacional de Investigaciones Científicas y Técnicas de la República Argentina, and visiting astronomer, Cerro Tololo Inter-American Observatory, operated by the Association of Universities for Research in Astronomy, Inc., under contract with the National Science Foundation.     

CCD surface photometry of the Seyfert 1 galaxy NGC 4151

We present CCD surface photometry of the central region of the bright Seyfert 1 galaxy NGC 4151. The observations were obtained under excellent seeing conditions (0.75 FWHM). Morphological parameters for the bulge of the galaxy are estimated from the observed broad bandV, R, andI surface brightness profiles.From the analysis of the colour maps two distinct nuclear structures emerge perpendicular to each other. One of them is elliptically elongated at PA angle 50°. This direction is close to the direction of the radio jets and coincides with the Extended Narrow Emission Line Region (ENELR). Its extension is about 7 arc sec and its colours are bluer than the surronding bulge. The second structure is smaller in extension (about 1 arc sec) and is elongated at PA130°. Its colours are redder than those of the surrounding bulge. It is suggested that this might constitute areal extension of the Broad Line Region (BLR).Paper presented at the 11th European Regional Astronomical Meetings of the IAU on New Windows to the Universe, held 3–8 July, 1989, Tenerife, Canary Islands, Spain.     

Mass-luminosity distribution and physical conditions of ionized gas in NGC 4575

Photographic photometry and spectroscopic observations of NGC 4575 suggest it to be a galaxy of reduced dimensionsD×d=14.4×13.5 kpc and of high luminosityM=–20.7. The rotation curve was also determined. Assuming a model of three homogeneous similar spheroids, we derived the density and mass distribution, and their total mass was found to be _T =2.33 × 10¹⁰.The mass luminosity ratio does not vary withinr=24, indicating that the stellar composition is similar within it, and the ratio _T / _T 1 suggests that this object contains a high proportion of young stars. From the emission lines it is found that the electronic density Ne100 cm^–3 is relatively low in the HII regions. The abundance ratiosN(N)/N(S) andN(N)/N(H) for the nucleus and two emission regions were also derived.     

Some fundamental elements of universe mechanics

An essential part in the mechanics under study is taking into consideration the effect of motions of the Universe objects upon that of an individual one surrounded by them including those infinitely far from it. Only macro-objects of the Universe are meant here.

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Zusammenfassung Ein wesentlicher Bestandteil der Mechanik unter unserer Betrachtung ist die Berechnung des Einflusses auf die Bewegung eines individuellen Objektes von Bewegungen der Universum Objekte die es umringen einschließlich jene Objekte, die unendlich entfernt sind. Nur Makroobjekte des Weltalles sind in der Absicht dabei.

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εлектроны космических лучей радиогало галактики

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The mid-IR radio correlation at high angular resolution: NGC253

We present high angular resolution (1.2), narrow band (/=0.1) images of the nucleus of NGC253 at three wavelengths in the mid-IR (8.5, 10.0, and 12.5 m). We find that most of the mid-IR flux in the nucleus of NGC253 derives from a very small region 120 pc in diameter. Within this small region there are three spatially and spectrally distinct IR components: two bright compact sources, and a surrounding envelope of low level, diffuse emission. The mid-IR and 6cm radio are loosely correlated in position but not in brightness. The implication is that the mid-IR - radio correlation may begin to break down on small spatial scales relevant to individual star forming regions and large individual sources. These variations in the mid-IR spectra and in the radio-IR correlation imply that the nuclear emission is excited by more than one mechanism and source type.     

О колебаниях хвоста магнитосферы в приБлижении квазигидро динамики

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The magnetic fields in M31, NGC 7331, NGC 2841, NGC 6946, and our galaxy

A time-independent model for the radial distributions of gas and magnetic field has been applied to the galaxies Milky Way, M31, NGC 7331, and NGC 2841, in order to explain the gaseous ring patterns in spiral galaxies, and to NGC 6946 to see if this model is valid for galaxies without a gaseous ring. The model takes the gas pressure as its input data and solves the MHD equations to calculate the magnetic field responsible for the gas distribution. This field has an azimuthal component only, and can be used to predict synchrotron radio emission. A discussion about the dependence of the synchrotron radiation profiles obtained upon the assumed relationN ₀(,B) for the cosmic-ray density per unit energy as a function of gas density and field strength, is here considered in detail. It is shown that a relation of the typeN ₀/B, which takes into account the loss of energy of the cosmic-relativistic electrons, yields good agreement with the observations.     

A study of the young open cluster NGC 6611

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Critical inclinations in planetary problems

The general conception of the critical inclinations and eccentricities for theN-planet problem is introduced. The connection of this conception with the existence and stability of particular solutions is established. In the restricted circular problem of three bodies the existence of the critical inclinations is proved for any values of the ratio of semiaxes . The asymptotic behaviour of the critical inclinations as 1 is investigated.

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Some peculiarities of four host galaxies,containing Seyfert nuclei

Star-like objects are found in Seyfert galaxies Markarian 290, Markarian 298, NGC 1275, and NGC 7469, being connected with the structure peculiarities of the galaxies. The absolute magnitudes of these objects are –16 ^m M–19 ^m . It has been supposed that these star formations must stimulate the instability in the disk of the galaxy followed by the matter fall toward the centre of the galaxy. The gas inflow toward the centre will allow the recent star formations and Seyfert nuclei generation.Paper presented at the 11th European Regional Astronomical Meetings of the IAU on New Windows to the Universe, held 3–8 July, 1989, Tenerife, Canary Islands, Spain.